A sign says, “Waste paper”. Underneath the sign is a box. You have to put your used paper in the box for recycling.
But, should the sign say “Waste paper” or “Paper Waste”?
The idea is that the first noun is a “noun modifier”, or, a “non-adjective”. This is like saying “wooden spoon”, or “plastic fork”. It's a spoon (second noun), not a “wood”. So when you say:
There's just one problem. If you say “Waste Paper”, then waste has waste-n and waste-v. Are you saying, “Please waste paper”? So, some people like to say “paper waste”.
However, maybe you could use the word “recycle”.
or
is great!